Art of stiffening portions of boots and shoes



Jan. 19, 1937. E sc wA z 2,957,98?

ART OF STIFFENING PORTIONS OF BOOTS AND SHOES Filed Aug. 5, 1935 O O O 0 o o 0)) o oio o 8 l/E/\/TU/? Patented Jan. 19, 1937 UNITED STATES PATENT OFFICE ART OF STIFFENING AND PORTIONS F BOOTS SHOES Application August 5,

1935, Serial No. 34,735

In Spain September 26, 1934 4 Claims.

This invention relates to the stiffening of portions of the uppers of boots and shoes by the use of a stiffening substance which is adapted to be softened by a volatile solvent.

In the manufacture of shoes it is common to use a stiffening substance, such as celluloid, which is inserted at the toe portion of a laminated upper between the layers thereof after having been previously softened by a volatile solvent such as acetone. The upper is then formed upon a last whereupon, after the solvent has been permitted to evaporate, a stiffened portion of the desired shape results. The layer of stiffening substance may be applied to one of the layers of the upper either at the toe portion or at the heel portion of the shoe in the form of a paste, a wafer or a piece of porous sheet material impregnated with the stiffening substance; and various stiffening substances and solvents may be employed.

In the manufacture of certain kinds of shoes, for example those having an outer layer of patent leather, the solvent or the solvent vapor sometimes works through the leather and has a deleterious effect on the varnish or finish on its dis play surface. This disadvantageous result is particularly liable to occur when the layer of stiffening substance is inserted between the outer or display layer of the upper and the adjacent lining, but it is also liable to occur even when a so-called doubler is used between which and the lining the layer of stiffening substance is inserted. It is, of course, possible to avoid injury to the finish of the leather by providing between the leather and the layer of stiffening substance a coating or guard member which is impervious to the solvent, but in such case the leather is not bonded to the layer of stiffening substance and to the remaining layer or layers of the upper; and this bonding of the various layers to each other is essential to the formation of a properly stifiened portion of the upper.

According to the method .of the present invention the stiffening substance is permitted to reach the outer layer (the leather layer of a patent leather shoe) of the upper only throughout part of the extent of the layer of stiffening substance.

By thus controlling the amount of softened stiffening substance which is permitted to reach the inner side of the outer layer of the upper, it is possible to permit enough to reach said inner side to form a strong bond between the outer layer and the adjacent layer without permitting, as has hitherto been the case, such a large amount to reach the inner side of v the outer layer that solvent or solvent vapor penetrates the outer layer to the detriment of the varnish. In practicing the method a perforate guard in the form of a thin flexible sheet of material impervious to the solvent and its vapor is preferably employed, the size of the perforations and their pattern being such as to produce the desired result.

Referring now to the accompanying drawing the figure is a full-sized plan of one of these guards suitable for use in stiffening the toe portion of the upper of a shoe.

This guard, which has the general shape of a toe stiffener, is made of a material such as waxed paper which is impervious to the solvent and the solvent vapor and is provided with an imperiorate margin 3 along its front and sides, the remaining portion of the guard being provided with perforations 5 which extend close to the rear edge 1. Assuming for example that in the manu'-- facture of a shoe having a patent leather vamp and a lining but no doubler there is to be used a stiffener consisting of a fabric blank impregnated with celluloid, the stiffener is softened by treating it with a solvent such as acetone and is then inserted between the vamp and the lining, a suitably shaped guard having perforations of the proper size and pattern being located between the blank and the leather vamp. All this is preferably done after the laminated upper has been assembled upon a last, the toe portion of the vamp being laid back to permit insertion of the toe stiffener and the guard. The upper is then subjected to the usual pulling-over and lasting operations whereby the upper is conformed to the last and a proper shape imparted to the toe portion. During the conforming of the parts of the upper to the last, the layers of the upperand the layer of stiffening substance are pressed firmly together; and there passes through the perforations of the guard an amount of stiffening substance sufficient to bond the vamp to the layer of stiffening substance but insufi'icient to cause solvent or vapor to pass through the vamp and thus injure the finish on the display side thereof. If the upper is provided with a doubler, the guard will preferably be inserted between the doubler and the lining and will have larger perforations, since the softened stiffening substance must work through the doubler into contact with the leather in order to insure that all the layers of the upper shall be firmly bonded together.

It should be noted that the margin along the front and sides of the guard is not perforated. In conforming the assembled upper to the last, the wipers of the lasting machine drag over the sides and front of the toe portion of the upper thereby subjecting the patent leather finish at this locality to a considerable rubbing action. It is very desirable therefore that this locality should be efiectively protected against any possibility of being softened by the solvent or solvent vapor. This protection of the margin of the toe portion of the upper is also desirable for another reason. It is customary, particularly in the manufacture of shoes the soles of which are attached by cement, to cut away the greater part of the lasting allowance of the toe stiffener (and the doubler if'present) at the toe portion of the shoe. In order to perform this trimming operation it is necessary to pull back the lasting allowance of the vamp so as to have access to the parts which are to be trimmed; and the imperforate margin of the guard insures that the lasting allowance of the vamp shall not adhere to the lasting allowance of the toe stiffener on the doubler and thus hamper the operator in his performance of the triim'ning operation.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. That improvement in stiffening portions of the laminated uppers of shoes, by the use of a stiffening substance adapted to be softened by a solvent which has a deleterious effect on the display surface of the outer layer of the upper, said method comprising introducing a layer of softened stifiening substance between layers of the throughout a part of the extent of the layer of stiffening substance.

2. That improvement in stiflening portions of the laminated upper of shoes having stiffeners adapted to be softened by treatment with a volatile solvent which comprises introducing between the softened stiffener and a layer of the upper prior to forming the upper upon a last, a guard in the form of a sheet of thin flexible material having a portion of its margin impervious to the solvent and its vapor, the remaining portions of the guard being pervious to said solvent and vapor.

3. A guard for shoe stiffeners consisting of or containing a stiffening substance adapted to be softened by a volatile solvent, said guard having a marginal portion which is impervious to the solvent and. its vapor, and another portion which is pervious to said solvent and vapor.

4. A guard for stifieners of the uppers of boots and shoes having stiffeners adapted to be softened by a volatile solvent, said guard comprising a thin flexible member made of a material which is impervious to the solvent and its vapor, said guard having an imperforate marginal portion and a perforate middle portion.

BRUNO E. SCHWARZ. 

